


Nightly Pleasures

by Mercyisnotasignofweakness



Category: Undertale (Video Game)
Genre: Depending on how you read this, Ecto-Penis (Undertale), Established Relationship, F/M, Gift Fic, Mildly Dubious Consent, Plot What Plot/Porn Without Plot, Rough Sex, Smut, Somnophilia
Language: English
Status: Completed
Published: 2016-12-24
Updated: 2016-12-24
Packaged: 2018-09-07 21:17:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,532
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8816524
Author URL: https://archiveofourown.org/users/Mercyisnotasignofweakness/pseuds/Mercyisnotasignofweakness
Summary: During the dark hours of night, you're faced with temptation. You promise yourself you'll tell Sans all about it tomorrow when he's awake, but right now you simply can't resist this maybe once in a life time opportunity anymore than you can ignore the pulse of heat beating between your legs.





	

**Author's Note:**

  * For [Life_sans_Sin](https://archiveofourown.org/users/Life_sans_Sin/gifts).



> To the lovely Brit, aka Sinmom. I hope you like your little spicy present. ;) Thank you for being such an incredible friend. I love you <3 I wish you and your family a wonderful Christmas and a happy New Year. May the next be even better for you, my dear. <3
> 
> \- Love Mercy
> 
>  
> 
>  
> 
> _Beta-read by[Pancakepants](http://pancakeuniverse.tumblr.com/) and [Shiv](http://shivra.tumblr.com/). Thanks for the help guys! You're the best! <3 ___

You are woken up by a noise. It takes you a moment to realize what has you blinking awake in the early hours of morning. The steady creaking of the bed has you confused for a few seconds while your brain catches up with your ears. When a broken moan tickles against the small hairs around your ear it dawns on you what you have now become a witness to. 

Sans is plastered against your back, his arms lying heavily around your waist. He’s squirming against you, his hips grinding against your ass in a slow, desperate attempt to get friction. The movements are clumsy and uncoordinated, obviously not something born out of a desire to play, but a wet dream driving him nuts. The small whimpers and moans escaping his teeth in between soft snores and deep breaths tells you as much. His fingers dig into the meat of your hips and clench around your pelvis. Their hold is rough and uncareful. Nothing like the sweet soft touches he normally showers you with, the ones that almost drive you completely insane every single time you are intimate together. The desire to have him just  _ fuck you senseless _ is a familiar burn in your belly by now. He never shows any sign of ever wanting to try something new. He always treats you like a something delicate and fragile.

A deep groan vibrates through his chest. It’s followed closely by a needy whine that tickles against your ear. Sans moves closer, like he’s trying to absorb you into his body. His weight and the jerky movements of his hips are enough to force your body to roll over. He goes almost crazy when he’s presented with a new angle to hump you at. His hips start grinding hard against your ass, like he’s trying to get deeper, closer. It makes your night gown slide up over your waist and exposes your dirty secret: You’re sleeping without panties. You had hoped to surprise him when you got home late from an appointment, but he had already been asleep. You fell asleep disappointed and horny. 

Another breathy moan gets caught between a snore and a half mumbled sentence containing your name. Sans nuzzles closer to your neck, burying his face in your hair. You feel his teeth nibble at the back of your neck and shoulder, the small, sharp stabs of pain from his bites only serving to make your pussy clench around the air, letting you feel how your folds are slowly getting covered by your wetness. He feels so strong lying on top of you like this, just taking whatever pleasure he can from you. It excites you way more than it should, to be used like this without him even knowing. You’re 100% sure that he would be horrified if he knew how he was treating you right now and that thought actually manages to make you moan.

“Fuck, Sans~” You whimper into your pillow, feeling guilty for the pulse of heat flowing through your belly at the thoughts that swarm your mind without permission. 

It would be  _ so _ easy to just spread your legs a  _ tiny _ bit and let him have his way with you…

It would be so wrong to do it. He doesn’t know what he’s doing and he will be so worried and sad when he wakes up tomorrow and finds you covered in the bruises you can already feel forming under your skin. But you want to do it  _ so much _ . The opportunity to feel him like this might never arise again, feel him while he’s not scared of leaving marks on your body. He can’t control himself right now and you want to be  _ ruined _ by him. 

You bite your pillow to silence your sounds and slowly slide your legs apart. If he wakes up you can always pretend that he did all this while you were still sleeping… But you already know you can’t lie to him like that. It’s one thing doing this, taking advantage of your boyfriend’s wet dreams to satisfy yourself, but you will not lie to him about it. You’ll tell him the truth when he wakes up. 

A particularly loud moan warns you of what is to come a split second before you feel it. Sans almost sobs in relief when he feels your legs spread apart, and he whimpers your name into your hair, his hold over your body tightening. His hips starts going crazy, making his newly manifested cock stab against your core in a desperate attempt to penetrate you. The head of his cock only barely manages to slip past your outer lips, searching for that place where the resistance will give in and be replaced with sweet, sweet pleasure. 

You can’t help it. You just can’t stop yourself. The sounds he’s making, the way he’s holding onto you like his life depends on it, even the way he whines your name makes it impossible to deny him, and yourself, much longer. 

“Please don’t wake up babe, please don’t wake up…” You whisper your words into the pillow seconds before your legs slide all the way apart to bare yourself to him fully. It instantly works. The new position suddenly allows Sans’ hips to move closer to yours and the head of his cock slides right up against your opening. It presses in about an inch before he pulls back with a whine. He tries a few more times, slamming his hips forward in a brutal way, but every time he never sinks deeper that the first inch. 

“Come on babe,” you encourage him. You arch your back, pushing your hips up to help him. A second later he bottoms out in you in one quick snap of his hips. Loud moans tumble out of both of you, leaving little to imagine for your neighbors. You bite into your pillow to muffle yourself and press backwards, greedily taking another half an inch of him into you. 

It’s like that kickstarts him. The jerky grinding snaps of his hips return at full force, accompanied by his distinct rise in volume. There’s no finesse to the way he fucks you, no gentleness or soft caresses like usual. He’s uses you for his own pleasure, unaware of the bruises and scratches he has littered all over your shoulders and hips. Your only function to him right now is to be a tool for his pleasure and you couldn’t be more turned on by the thought, even if you tried. 

“Yes baby, come on. Fuck me like you mean it,” you encourage him softly. He’s asleep and can’t hear you, but your soft murmur of words makes you feel powerful, makes you feel like you’ve gotten him to be like this. That you are controlling him. You’re not just being used, you are  _ allowing _ him to use you.

The cock he has conjured this time is so much bigger than the one you are used to. There’s something about that, that excites you even more. He normally makes it to fit you perfectly, never too big or too small. Now it’s almost too big, spreading you apart in the most delicious way. 

It’s not going to last for long. You know that. You can already feel his body trembling in the telltale way it always does right before he comes. If he had been awake he would be cursing your name right now and trying to hold on until you had come. But he doesn’t. He never slows down and never loosens his grip on you. 

He slams himself into you when he comes, forcing his cock as far back as possible, like he’s trying to keep his cum inside you. When he’s done he doesn’t roll of you instantly either like normal. Instead he just kind of deflates, almost like he falls into a much deeper sleep. His cock doesn’t disappear instantly either and that’s what makes you curse and bite your pillow again. You didn’t get to finish and your pussy is clenching around him desperately. Sans’ hips are still grinding against your ass sometimes, providing small stabs of pleasure that keeps you on the edge, but he’s obviously falling into a deeper sleep. His body is dead weight against you. 

Frustrated doesn’t even begin to describe how you are feeling. You’re  _ so close _ . A hand finds it way down to your folds. It’s so easy to press a couple of fingers to your clit and tilt your hips up, making Sans slide deeper into you. 

You begin the slow climb towards orgasm, slowly fucking yourself on Sans’ cock and rubbing your clit. It doesn’t feel as great as when he was fucking you, but his cum trapped inside you makes the slide of his cock so much more pleasurable against your g-spot. 

The pillow is the perfect gag for you to muffle your sounds when you’re going to come. Your pussy clenches around Sans, making him whimper. He still doesn’t move, but you don’t care. The waves of pleasure crashing through you are making you sleepy really fast. You actually manage to fall asleep before you finish.


End file.
